Large queries spilling into tempdb such as SQL Server – SORT IN TEMPDB and Sort Warnings and large temporary tables can use Tempdb space very quickly and lead to outages. Use the DMVs : sys.dm_db_file_space_usage, sys.dm_db_session_space_usage, sys.dm_db_task_space_usage

How to Troubleshoot TempDB

First Step - Comprehensive Tempdb Sizing exercise. There are many different methods , such as : a) create a workload b) running large maintenance jobs e.g index rebuild

Second Step - monitoring Tempdb usage. As well as a SQL Server monitoring alerts solution based on events , such as disk full, there are some useful DMVs to drill into TempDB usage based on tasks and sessions.